For more than two decades, federal and state agencies have been trying to prevent Asian carp from taking hold in the Great Lakes. Part of the prevention is limiting the spread of carp in the Mississippi River Basin, which stretches from northern Minnesota to the Gulf of Mexico.
Federal agencies have been teaming up with state fisheries up and downriver to curb the carp’s hold on the Mississippi’s aquatic ecosystem, including Kayla Zankle, she’s the Minnesota Department of Natural Resources’ invasive carp field lead. When we talked this week, Zankle was puzzling out a better way to catch Asian carp.
"Hopefully it will be ready to go when the water gets a little warmer this spring. What we’re trying to do is to design a net to prevent or discourage silver carp from jumping," Zankle says.
If any species is recognizable it’s silver carp, thanks to videos of the large fish leaping high into the air. It’s one of four carp species mucking around parts of the Mississippi basin. Zankle says closer to the headwaters, "We haven’t found any black carp. We have had grass carp since the 1970s, bighead since 1996 I think, and silver in 2008," she says.
No one knows for sure how many carp populate the entire Mississippi basin — estimates range in the millions, but Zankle notes, "We haven’t seen large numbers here."
Zankle says she and her partners hope to keep the Mississippi waters shared by Minnesota and Wisconsin that way. So her team are netting and removing as many carp as possible 11 months of the year.
"I hope we can continue to remove them as fast as they come, I know that’s a big ask, but I think its doable if we continue to work together as well as we have," Zankle says.
Zankle describes the work as “going a thousand miles an hour” but says, thanks to a network of partners, including the U.S. Fish & Wildlife Service and deploying telemetry technology that allows them to track carp, she’s encouraged.
"We had a multiagency netting this fall. We can track these fish and we find them in schools of six to seven fish. That’s how we were successful in removing 408 at the beginning of the month," she says.
Kristina Pechacek and her fisheries team steps in to help whenever they can. Pechacek is Mississippi River fisheries biologist with the Wisconsin DNR. She says removing carp is sometimes grueling.
"The last event we went out, we were standing in waders in a shallow area … and so we’re basically in a large net pen. And you’re walking among thousands of fish to try to find the one invasive fish that is very large. They’re not small fish by any means and they’re heavy. It can be a little treacherous sometimes, especially when you’re only 5 foot 2," Pechacek says.
But Pechacek says it’s important work. She thinks others might benefit, including their Great Lakes counterparts.
"This whole process of us learning and working together — multi agencies — is giving us so much information on how to work together collaboratively and target these fish. Hopefully, nothing happens in the Great Lake, but if it does, they can learn from what we’ve done here and be proactive," Pechacek says.
For now though, these two biologists’ attention is riveted on Wisconsin and Minnesota waters of the Mississippi. Kayla Zankle says they have to prevent carp from spawning here. Why? Zankle says carp are considered mass spawners, "What that means is the females can broadcast out about a million eggs. And if all of all those eggs are fertilized and successfully hatch - and given the correct conditions it could be anytime from 24 to 72 hours after they spawn, these things can hatch. When that happens, the population just explodes," she says.
Zankle says the ravenous eaters consume vast amounts of plankton and water insects. "Most people don’t realize even our game fish rely on plankton and insects at some point in their life cycle," Zankle says.
Wisconsin colleague Kristina Pechacek says, "If we start getting higher numbers, it will definitely affect our native fish species."
No one, they say, wants to see that happen.
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